Localization of thiazide-sensitive Na⁺-Cl⁻cotransport and associated gene products in mouse DCT

Abstract

tion of thiazide-sensitive Na ϩ -Cl Ϫ cotransport and associated gene products in mouse DCT. Am J Physiol Renal Physiol 281: F1028-F1035, 2001. First published August 8, 2001; 10.1152/ ajprenal.00148.2001.-The mammalian distal nephron develops a complex assembly of specialized cell types to accomplish the fine adjustment of urinary electrolyte composition. The epithelia of the distal convoluted tubule (DCT), the connecting tubule (CNT), and the cortical collecting duct (CCD) show an axial structural heterogeneity that has been functionally elucidated by the localization of proteins involved in transepithelial ion transport. We compared the distribution of the thiazide-sensitive Na ϩ -Cl Ϫ cotransporter (TSC), basolateral Na ϩ /Ca 2ϩ exchanger (Na/Ca), cytosolic calcium-binding proteins calbindin D28K and parvalbumin, and the key enzyme for selective aldosterone actions, 11␤-hydroxysteroid-dehydrogenase 2 (11HSD2), in the distal convolutions of the mouse. In the mouse, as opposed to the rat, we found no clear subsegmentation of the DCT into a proximal (DCT1) and a distal (DCT2) portion. The TSC was expressed along the entire DCT. Na/Ca and calbindin D28K were similarly expressed along most of the DCT, with minor exceptions in the initial portion of the DCT. Both were also present in the CNT. Parvalbumin was found in the entire DCT, with an occasional absence from short end portions of the DCT, and was not present in CNT. 11HSD2 was predominantly located in the CNT and CCD. Short end portions of DCT only occasionally showed the 11HSD2 signal. We also observed an overlap of 11HSD2 immunoreactivity and mRNA staining. Our observations will have implications in understanding the physiological effects of gene disruption and targeting experiments in the mouse. distal convoluted tubule; connecting tubule; sodium-calcium exchanger; calbindin; parvalbumin; 11␤-hydroxysteroid-dehydrogenase type 2 MAMMALIAN KIDNEYS ARE CAPABLE of adapting urinary sodium and chloride excretion according to intake across a wide range of salt intakes with high precision. The fine adjustments take place in the distal nephron. Successive portions of the renal tubule are formed to adapt to this function, and an axial heterogeneity of the distal segments has been defined (11, 13). In the cortex, the thick ascending limb of Henle's loop (TAL), the distal convoluted tubule (DCT), the connecting tubule (CNT), and the collecting duct (CCD) have been identified. The specific transport properties of these epithelia are accomplished by the expression of proteins representing cotransporters, exchangers, and ion channels. These proteins govern ion movement from one side of the cell to the other. The distribution, ontogeny, and functional aspects of these proteins in the mammalian distal nephron have been reviewed elsewhere (2, 23). In the rat, the electroneutral cationchloride cotransporter (NaϪ ) has been localized to the TAL (11). The thiazide-sensitive Na ϩ -Cl Ϫ cotransporter (TSC; also termed NCC) has been localized to the more proximal (DCT1) and di...

Hypertrophy in the Distal Convoluted Tubule of an 11β-Hydroxysteroid Dehydrogenase Type 2 Knockout Model

“…Transcripts expressed in the distal tubule were present in greater abundance in Hsd11b2 2/2 kidneys than in the wild types (Table 1). Transcripts expressed in the DCT (NCC, parvalbumin, L-SPAK, and KS-WNK1 36,37 ) were more abundant, as were those expressed predominantly in the CNT or CCD (ENaC, NCX1, Trpv5, and calbindin-D28k), indicating that a molecular adaptation to increased solute transport extended into these segments.…”

“…It is possible that 11bHSD2 expression was below the detection sensitivity of our immunofluorescence or PCR approaches, but others have reported similar findings. 36,41 This suggests that protection of MR by 11bHSD2 is less robust in the DCT than in the CNT and CCD, a concept with implications for corticosteroid signaling in these cells. Because the DCT expresses both the MR and glucocorticoid receptor, Na + transport is not likely to be regulated solely by the canonical aldosterone signaling pathways present in principal cells; glucocorticoids may exert a stronger influence here than in the CNT and CCD.…”

Citric acid cycle intermediates as ligands for orphan G-protein-coupled receptors

“…In situ hybridization, immunohistochemistry and expression analysis These were performed as described 10,25 . [ 33 P]UTP-labelled antisense or sense RNA probes for mouse GPR91, GPR99 or renin were hybridized to paraformaldehyde-fixed, paraffinembedded mouse kidney sections.…”

“…AQP0 is a member of the aquaporin family, members of which form pores that are either highly selective for water (aquaporins) or also permeable to other small neutral solutes such as glycerol (aquaglyceroporins) (reviewed in ref. 10). To date, the atomic structures of three aquaporins have been determined (AQP1 [4][5][6] , GlpF 7,8 and AQPZ 9 ).…”

“…4d). GPR91 was also found, to a smaller extent, in the distal tubules (revealed by staining with antibodies against the distal-tubule marker calbindin 10 ; Fig. 4d) and the juxtaglomerular apparatus (Supplementary Information).…”